Automatically-connecting electrical connector

ABSTRACT

A device for connecting multiway connectors to each other or to electrical equipment enables elastic energy to be stored during the first part of its connecting travel and to be returned during the second part as a force pulling the device to its travel-limit position thus enabling the automatic complete connection of the connectors and reliable electrical contact to be achieved automatically.

BACKGROUND OF THE INVENTION

The invention relates to an electrical connector for multiwayconnections in the electrical system of a motor vehicle.

Electrical connections between the battery and electrical accessories ofa motor vehicle are made by means of male/female electrical terminals(also called "pins") carried by multiway connectors (also commonly knownas blocks).

This facilitates electrical connection at the assembly stage and enablesthe electrical equipment of a motor vehicle to be maintained andreplaced during the vehicle's lifetime.

The connection normally consists of two complementary half-connectors(male and female) which are joined together.

The problem inherent in connections of this type is the possibilitythat, during assembly, the operator may interconnect the twohalf-connectors only partially (not fully); this partial connectionnaturally does not show up during testing since it is able to transmitcurrent temporarily but may cause the half-connectors to come apartlater, during use of the vehicle, because of vibrations, with theconsequent disconnection of the services dependent on the connectorsconcerned.

It has also been proposed (British patent application No. 2 169 758) toprovide one half-connector with resiliently-deformable elements in orderto increase the force needed for the insertion of the half-connector upto an intermediate point, called the "dead point", so as then to makeuse of the resulting impulse to reach the travel limit.

Even this type of connector has some disadvantages, however, again dueto the possibility of only partial connection during assembly.

SUMMARY OF THE INVENTION

The present invention proposes to solve the problems mentioned above soas to provide an electrical connector which is reliable, strong, cheapand easy to handle. The objects are achieved, according to theinvention, by an electrical connector comprising a first half-connectorcarrying male or female terminals of a first ribbon of cables and asecond half-connector carrying female of male terminals of a secondribbon of cables, one of said half-connectors including a resilientdevice which stores energy during a first stage in connecting saidhalf-connectors and which can return the stored energy to enableautomatic connection of the first and second half-connectors during asubsequent second stage in connecting said half-connectors, saidresilient device for restoring energy comprising a substantiallyU-shaped spring having a pair of diverging free ends in the unstressedstate, securing means in the first half-connector engaging the springand securing said spring in said first half-connector with said springdisposed symmetrically with respect to a longitudinal axis of theconnector, said second half-connector having a pair of spaced apartwalls with oppositely inclined surfaces which are each inclined at anangle β to the longitudinal axis of the connector, said walls havingspaced apart free corners where the walls are closest which causeelastic deformation of the U-shaped spring as the spring passes betweenthe corners during connecting of said half-connectors until said freeends of said spring pass the spaced apart corners of said walls, wherebyengagement of said free ends of said spring with said inclined surfacesallows said spring to be restored toward said unstressed state and togenerate a force to complete inserting said first half-connector intosaid second half-connector.

The dependent claims give some advantageous solutions of the electricalconnector according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and characteristics of the will become clear withreference to the appended drawings, in which:

FIGS. 1 to 4 show the electrical connector according to the inventionduring the stages of connection of two half-connectors;

FIG. 5 shows the elastic-energy-storage device of the connectoraccording to the invention;

FIGS. 6a and 6b indicate qualitative changes in some quantities whichcome into play during the connection;

FIGS. 7a and 7b indicate quantitive changes in some quantities whichcome into play during the connection;

FIG. 8 shows some positions of the elastic-energy-storage deviceaccording to the invention during its connection travel;

FIG. 9 shows the qualitative variations in the pulling force withvariations in the angle of inclination of the bearing surface of theenergy-absorption device according to the invention;

FIG. 10 shows the changes in the forces which come into play during theentire connection travel.

DETAILED DESCRIPTION OF THE INVENTION

The embodiment of the electrical connectors according to the inventionrelates to the mechanical and electrical connection of two separateribbons of cables 9 and 10 but the invention is also suitable for a casein which a half-connector, such as 1, is to be inserted in acorresponding seat in electrical equipment carrying electricalconnections.

The electrical connector according to the invention consists of a firsthalf-connector 1 carrying within it male/female electrical cableterminals, also called pins (not shown in the drawings), of a ribbon ofcables 9 and a second half-connector carrying within it male/femaleelectrical cable terminals, also called pins, of another ribbon ofcables 10. A U-shaped spring 4 having a pair of diverging free ends inthe unstressed state is fixed at 3 in the half-connector 1 with the axisof symmetry of the "U" coincident with the longitudinal axis of theconnector according to the invention.

In correspondence with the position in which the spring 4 will besituated after connection, the half-connector 2 has walls 11 withinclined surfaces 7. The insertion of the half-connector 1 into thehalf-connector 2 is achieved in the following manner: the twohalf-connectors 1 and 2 are placed face to face with the spring 4 andthe wall 11 in contact with each other; at this stage, the force Fo (theforce exerted on the half-connectors by the operator) is zero (FIGS. 1and 2).

As the insertion travel is continued (FIG. 3), the force Fo increases invalue because of the loading of the spring 4 until the two arms 6 of thelatter reach the "dead point", that is they come into contact with thecorners 7' of the walls 11; in this position, the spring 4 has storedall the elastic energy and the operator has exerted the maximum forceFo.

Electrical contact between the pins of the half-connectors 1 and 2 hasnot yet been achieved at this moment; it occurs only after the "deadpoint".

As soon as the "dead point" is reached, the half-connector 1 is pulledinto the half-connector 2 by the elastic force stored in the spring 4whose arms 6 act on the inclined planes 7 which are arranged so as topull the two half-connectors 1 and 2 towards each other.

During this travel, in order to keep the two half-connectors 1 and 2 inequilibrium, it would be necessary to reverse the force Fo exerted fromoutside.

The spring 4 therefore develops a force Fr, a pulling force, whichensures the complete and automatic connection of the two half-connectors1 and 2, that is without any force on the part of the operator, enablingthe connection of the male/female pins of the block and also overcomingthe resulting friction.

When they have reached their travel limit, the two half-connectors areconnected permanently by a positive engagement (not shown in thedrawings) which can be released in known manner so that the twohalf-connectors 1 and 2 can be separated and the two ribbons of cables 9and 10 disconnected.

If friction is left out of consideration, the force Fo depends on theangle of the spring 4 as well as on its geometry and resilientcharacteristics, the angle meaning, more precisely, that which is formedbetween the longitudinal axis of the connector and the tangents to thetwo arms of the spring 4 at their points of contact with the corners 7'of the walls 11; this angle varies during the connection travel from aninitial maximum to a minimum when the "dead point" is reached and thenincreases again during the "pulling".

The force Fr depends on the orientation of the inclined surfaces 7 ofthe walls 11 and on the elastic force stored in the spring 4.

It should be noted that the U-shape of the spring 4 is only an example,since it is possible to think of other configurations with any othertype of resilient device for storing the energy obtainable during thefirst stage of the connection travel. For example, a helical springcould be inserted between the two arms 6 of the spring 4, perpendicularto the longitudinal axis of the connector, for storing elastic energy.In this case the two arms of the "V"-shaped device could be rigid andhinged at the vertex of the "V".

The resilient element of the engagement system may be the spring 4alone, as indicated in the drawings, or the walls 11 may be resilient soas to absorb energy, the U-shaped device being rigid. It is evenpossible to combine the two extreme cases, that is a spring 4 and walls11 which are both resilient so as to absorb energy.

As stated, the electrical contact takes place only after the "deadpoint", thus ensuring that it is impossible for the operator to connectthe two half-connectors 1 and 2 only partially. In fact, (once theoperator is no longer exerting the force Fo (FIG. 2)), the twohalf-connectors are either completely connected (FIG. 4) or they aredisconnected so that, even in the event of a connection not beingachieved, this anomaly is immediately shown up and corrected upontesting.

With reference to FIGS. 5 to 10, the changes in the forces which comeinto play will now be explained. The graphs have been determined withthe sliding friction between the contact surfaces of the spring 4 andthe walls 11 being ignored for simplicity of explanation. Naturally, thefriction, which is present in reality, will be such as to require theoperator to exert a greater force Fo to achieve the same elasticdeformation as in the case of zero friction. Similarly, when the"pulling" force comes into play, the force available for the connectionof the electrical pins will be less, for a given elastic deformation ofthe spring 4, because of the friction.

FIG. 5 shows the position of the spring 4 during the insertion of thehalf-connector 1 into the half-connector 2 in continuous outline and itsinitial position and the "dead point" position in chain line. In FIG. 5,the following values are shown: α=the angle of the arms 6 (according tothe definition given above), the indices "i" and "o" indicating itsinitial value and its dead-point value respectively.

Fo=the force applied by the operator to the half-connector 1,

Fo/2=the reaction force exerted by the restraints along the axis of theconnector,

Fe=the elastic deformation force,

If, as stated, the frictional forces are ignored, then by simplemathematical steps:

    Fe=Fo/2×1/sinα

From a study of this formula it can be seen that, for a given force Fo,the resilient force Fe is greater the smaller the angle α.

FIGS. 6a and 6b show qualitative changes in the angle α and in theelastic deformation force Fe during the connection travel up to the"dead point" indicated xo.

FIGS. 7a and 7b show a numerical example of the values of the angle αand of the elastic force Fe respectively on the ordinates as functionsof the connection travel.

FIG. 8 shows some positions of the spring 4 during its pulling travel,together with a graphical representation of the forces, the slidingfriction of the arms 6 on the surfaces 7 of the walls 11 being ignored,as already stated. Thus, by simple steps:

    Fe=F.sub.r /2tgβ

β being the angle between the inclined surface 7 and the longitudinalaxis of the connector.

It can be seen that, for a given stored elastic force, the pulling forceFr is the greater the greater the angle β.

On the other hand, the travel achieved by the pull up to the completerestitution of the stored elastic energy (Fe=0) is naturally smaller thegreater the angle β. The optimum value of β must therefore reconcile twoconflicting requirements, which are:

a) to maximise the pulling force Fr for a given elastic force Fe up tothe point of complete connection;

b) to maximise the travel due to the pull in order to ensure thecomplete connection of the male-female contacts.

A good compromise is given when β is between 40° and 50°.

FIG. 9 shows the qualitative changes in the elastic force Fe and in theforce Fo acting along the longitudinal axis of the connector asfunctions of the connection travel. The family of curves after the pointxo ("dead point") has been crossed indicates how the pulling force Frchanges with variations in the angle of inclination β of the inclinedsurfaces 7 of the walls 11.

FIG. 10 shows the qualitative changes in the forces which come into playin the connector throughout the connection travel. As well as thechanges in the forces Fe, Fo and Fr already described with reference tothe preceding figures, the mechanical characteristic of the force Fa forthe connection of the electrical terminals, also known as pins, is alsoshown.

It can be seen that the pulling force Fr is such as to exceed the forceFa for connecting the electrical terminals so that the equilibriumbetween the two forces takes place downstream of the positive engagementpoint shown by the broken line 8 in the drawing.

Moreover, it is clearly shown in FIG. 10 that electrical contact startsto occur downstream of the "dead point" so that electrical contact isnot possible when the pins are only partially connected.

If friction is ignored, the energy stored during the first stage isequal to the energy returned during the second stage, that is, as afirst approximation: ##EQU1## where 1₂ and 1₁ are the longitudinalcomponents of the arms of the spring 4 and of the inclined surfaces 7respectively. From this formula it can be deduced that the pulling forceFr can be made greater than Fo in order to ensure the automaticconnection of the two half connectors by changing the geometry of theenergy-storage system, in this case for example, by increasing 1₂relative to 11.

What is claimed is:
 1. An electrical connector for multiway connectionsin an electrical system of a motor vehicle comprising:a firsthalf-connector carrying male or female terminals of a first ribbon ofcables and a second half-connector carrying female or male terminals ofa second ribbon of cables, one of said half-connectors including aresilient device which stores energy during a first stage in connectingsaid half-connectors and which can return the stored energy to enableautomatic connection of the first and second half-connectors during asubsequent second stage in connection said half-connectors, saidresilient device for restoring energy comprising a substantiallyU-shaped spring having a pair of diverging free ends in the unstressedstate, securing means in the first half-connector engaging the springand securing said spring in said first half-connector with said springdisposed symmetrically with respect to a longitudinal axis of theconnector, said second half-connector having a pair of spaced apartwalls with oppositely inclined surfaces which are each inclined at anangle β to the longitudinal axis of the connector, said walls havingspaced apart free corners where the walls are closest which causeelastic deformation of the U-shaped spring as the spring passes betweenthe corners during connecting of said half-connectors until said freeends of said spring pass the spaced apart corners of said walls, wherebyengagement of said free ends of said spring with said inclined surfacesallows said spring to be restored toward said unstressed state and togenerate a force to complete inserting said first half-connector intosaid second half-connector.
 2. A connector according to claim 1, whereinthe angle β is between 40° and 50°.
 3. A connector according to claim 1,wherein a longitudinal component of the length of the arms of theU-shaped spring is greater than a longitudinal component of the lengthof the inclined surfaces.
 4. A connector according to claim 1, wherein alongitudinal component of the length of the inclined surfaces is greaterthan or equal to a distance necessary to achieve electrical coupling soas to prevent partial electrical coupling.
 5. A connector according toclaim 1, wherein the walls with inclined surfaces are rigid.
 6. Aconnector according to claim 1, wherein the walls with inclined surfacesare themselves resilient.
 7. A connector according to claim 1, furthercomprising an engagement system for preventing accidental release of thetwo half-connectors.